The attacks in Yala province on Wednesday night followed a security sweep by government forces in the region this week in which 120 Muslim suspects were held for questioning, police and army officials said.

Among the latest casualties in a Muslim separatist campaign that started in 2004, five people were killed in Yala and neighbouring Pattani province on Wednesday, including two public health workers shot dead at their clinic.

More than 2,300 have been killed in almost daily violence in Yala, Pattani and Narathiwat provinces, a Malay-speaking former sultanate annexed by Thailand about a century ago.

The militants in the latest bout of separatism in the region bordering Malaysia never claim responsibility for attacks or set out their aims.